Swarms of desert locusts that began appearing over the past few months in parts of Mali threaten to spread northward into Algeria, Libya, Morocco and Mauritania, according to the United Nations Food and Agriculture Organization.

The swarms are believed to have initially emerged last year in the Libyan conflict zone, fed by abundant rainfall and unusually lush and moist conditions during the past summer.

The insects originate from certain regions in North Africa or the Middle East, and proliferate when rainy seasons become unusually wet. That's what happened earlier this year.

This is why plagues of locusts are known as “the curse of the rains.”

The insects can consume more than their own weight in vegetation each day, and can ravage crops and pastures within hours.

New tracking and spraying technologies, once carried out on foot and by camel, promise to help prevent the extensive crop damage and resulting famine the insects have inflicted on the Sahel region for centuries.